Megachile (Megachiloides) subnigra Cresson, 1879

Megachile subnigra Cresson, 1879: 208 .

Megachile (Xeromegachile) subnigra; Mitchell 1937a: 364; 1944: 138. Hurd 1979: 2065. Ivanochko 1979: 252.

Megachile (Megachiloides) subnigra; Raw 2002: 21. Scott et al. 2011: 56. Sheffield et al. 2011. Reese et al. 2018: 22. Delphia et al. 2019a: 25. Sheffield and Heron 2019: 70.

Megachile (Xeromegachile) angelica Mitchell, 1934: 318 .

Megachile (Xeromegachile) blaisdelli Mitchell, 1934: 336 .

Megachile (Xeromegachile) moschata Mitchell, 1934: 338 .

Diagnosis. The female of M. subnigra can be identified by its all-black scopal setae on S2–6 and 4-toothed mandibles with a pointed basal mandibular tooth (Fig. 7B). The female of M. subnigra is most similar to M. gemula, which has reddish-brown scopal setae on S2–6 and a truncate basal mandibular tooth (Fig. 7E). For further details on identification issues see Taxonomic Challenges. The male of M. subnigra can be identified by the mostly black pubescence on the mid and hind legs, cream to yellow colored protarsi, and the wide, spatulate procoxal spine (Fig. 8I) with a short suberect patch of setae at the base.

Notes. Megachile subnigra is known from the southern half of central Montana, in the upper Yellowstone and upper Missouri drainages (Fig. 1 AG). Photographs, a full morphological description, and notes on the biology of this ground-nesting species can be found in Sheffield et al. (2011).